1. Field of the Invention
This specification relates to an apparatus and a method for measuring cholesterol, and more particularly, to an apparatus and a method for effectively measuring cholesterol using a small amount of blood.
2. Background of the Invention
As a population structure is changed into an aging society recently, concerns for health are increased. In such a situation, equipment of health diagnosis is highly required, and the equipment has a high possibility to be presented on a new market.
Generally, a patient's medical examination is performed by analyzing the patient's body fluid, and then by measuring the amount or concentration of a material (index material) included in the body fluid, the material related to the patient's health state such as disease or pregnancy. The index material is measured by extracting the patient's body fluid, and by performing a bio-chemical reaction such as an antigen-antibody reaction with respect to the index material. In the past, since an experimental drug or equipment requiring professional knowledge is used, high costs and longer time are required. Further, a patient should go to hospital for diagnosis. This may cause many restrictions to the patient.
In order to overcome such disadvantages, a point-of-care test (POCT) is being spotlighted. The POCT means a test for diagnosing a patient within a short time by immediately extracting a body fluid of the patient and analyzing the body fluid, on the spot where the patient is positioned.
The POCT is being widely used owing to its various advantages that a patient can perform self diagnosis in a simple manner, additional costs and time can be reduced, etc. Among such bio-chemical POCT items, cholesterol (TG, TC, HDL, LDL), blood sugar (Glucose) and a liver function (AST, ALT), etc. are much used. A biosensor for measuring such items is configured to perform its function using electrochemistry and optics (LED, PD).
An apparatus for measuring cholesterol applying optics (biosensor) uses a color-development reaction. In case of applying the biosensor using a color-development reaction, a solution itself may be used as a medium for moving or measuring fluid, or membranes may be used.
FIG. 1 is a schematic view illustrating an apparatus for measuring cholesterol in accordance with the conventional art.
As shown in FIG. 1, a user may insert a cartridge 20 into a cartridge accommodation unit (not shown) of an apparatus for measuring cholesterol 10, and then may inject blood into the cartridge 20 through a blood injection opening 12. Alternatively, the user may firstly injects blood into the cartridge 20, and then may insert the cartridge 20 into the cartridge accommodation unit.
FIG. 2 is a view illustrating a detailed structure of a cartridge inserted into the apparatus for measuring cholesterol.
As shown in FIG. 2, the conventional cartridge 20 includes an upper case 1 having a filtering membrane 1a and a spreading membrane 1b, and a lower case 3 having spreading membranes 3a and reaction membranes 3b. End portions of the upper case 1 and the lower case 3 are fixed to each other by an elastic member 2.
The filtering membrane 1a serves to transfer serum by filtering red blood cells (RBCs) from blood injected through the blood injection opening 12 of the apparatus. The spreading membrane 1b serves to spread the transferred serum. Especially, the spreading membrane 1b of the upper case 1 is a moving path of fluid, and a length thereof is the same as a distance between two membranes positioned at two ends of the lower case 3.
FIG. 3 is a view illustrating a cholesterol measuring operation using an apparatus for measuring cholesterol in accordance with the conventional art.
As shown in FIG. 3, if the cartridge 20 is inserted into the cartridge accommodation unit (not shown) of the apparatus for measuring cholesterol 10 and then blood is put to the cartridge 20 through the blood injection opening 12, serum of the blood, obtained after red blood cells (RBCs) are filtered by the filtering membrane 1a, is transferred to the spreading membrane 1b. Then, if the cartridge 20 is vertically moved by a driving means, the spreading membrane 1b of the upper case contacts the three spreading membranes 3a. As a result, the serum is transferred to three reaction membranes 3b from the spreading membrane 1b, through the three spreading membranes 3a. Then, the cartridge 20 is moved to the original position by the driving means. Then, light is projected onto the reaction membranes 3b by an optical unit (LED, PD), thereby checking a color-development reaction of the reaction membranes 3b. As a result, three types of cholesterol items (TC, TG, HDL) are simultaneously measured. The measured cholesterol level is displayed on a display unit.
In case of simultaneously measuring three types of cholesterol items (TC, TG, HDL) in the conventional apparatus for measuring cholesterol, in order to transfer serum obtained after red blood cells (RBCs) are filtered from blood, to the reaction membranes 3b, a moving path of liquid (serum), i.e., the spreading membrane 1b should be provided.
However, if the moving path of liquid is implemented as the spreading membrane 1b, a dead volume, a phenomenon that the spreading membrane 1b includes a large amount of fluid by absorption and spread of the fluid while the fluid flows, is generated.
As a result, a minimized amount of fluid for measuring cholesterol is not uniformly transferred to the reaction membranes 3b, or a small amount of fluid is transferred to the reaction membranes 3b, resulting in inaccurate measurement result values. Further, a larger amount of fluid (blood) should be used for a more precise measurement result values.
In the conventional apparatus for measuring cholesterol, blood reactions and processes according to each step are not separated from each other, but cholesterol items are measured through consecutive reactions. This may degrade process efficiency due to remaining fluid, fluid loss, interference between processes, etc. Especially, when a consecutive reaction processor is consecutively used, efficiency and performance according to each reaction step cannot be monitored. This may cause a failure rate of the entire system to be increased, and may cause a difficulty in actively controlling each step for enhanced efficiency according to each reaction step.
Further, in most of point of care test (POCT) equipment such as the conventional apparatus for measuring cholesterol, blood is taken by an additional subsidiary device for blood collection. Then, the collected blood is injected into a cartridge. Using such two steps may cause a user's inconvenience.